"I leaked nothing to nobody," she told MSNBC on Tuesday afternoon.
"If I saw an intelligence report that looked potentially significant ... I can make that request," Rice said of unveiling names of American citizens in intelligence reports. "That's necessary for me to do my job."
Bloomberg and Fox News reported this week that Rice requested the names of Trump transition officials be unveiled in classified intelligence reports about foreign citizens.
She said that unmasking a name in an intelligence report reveals the name only to the person who requested it and that doing to cannot be compared with leaking the name to others broadly in the U.S. government. "There is no equivalence between so-called unmasking and leaking," she said.
"There were occasions when I would receive a report in which a U.S. person was referred to — name not provided — just 'U.S. person.' And sometimes, in that context, in order to understand the importance of the report and assess its significance, it was necessary to find out or request the information as to who the U.S. official was," Rice said. "The intelligence community made the determination as to whether or not the identity of that American individual could be provided to me."
A former national security official close Rice would not deny to ABC News that during the course of her official duties she may have unmasked officials connected to the Trump transition team and campaign but insisted that she would have never done so improperly.
"I'm not denying that she routinely requested the unmasking of individuals," the source said, adding that any instance of unmasking would have been necessary to understand the value of the intelligence being presented to her.
House Intelligence Committee Chair Rep. Devin Nunes, R-Calif., previously said he was concerned that former Trump campaign associates were named in intelligence documents about the federal government's investigation into Russia's meddling in the 2016 election. Nunes said the classified documents show Trump associates may have been incidentally surveilled, but the committee's ranking member, Rep. Adam Schiff, D-Calif., said he does not agree with that assessment.
"To talk about the individuals on the foreign side, who were the targets of the report itself, or any Americans who may have collected upon incidentally — is to disclose classified information. I'm not going to do that," Rice said, saying that giving details about classified reports is "very wrong."
"When it is necessary to unmask a name to understand the significance of the communication, there is a process for doing so, which is also lawful. Our committee routinely reviews whether our intelligence agencies are properly masking names and unmasking them as appropriate," Schiff said in a statement on Tuesday. "Some incidental collection is unavoidable, and as long as proper procedures are being followed, it is fully lawful. It does not constitute either wiretapping or surveillance of Americans."
White House press secretary Sean Spicer said Tuesday the reports were concerning.
"There is a civil liberties component to this that should be very troubling," he said. "So the question is, why was someone unmasked, if that's the case? I believe there are more questions than answers at this point."
Trump tweeted a month ago that then-President Obama wiretapped Trump Tower in New York during the 2016 presidential campaign. The leaders from both parties in the House and Senate, the two chambers' intelligence panels and top current and former intelligence officials have said there's no evidence to support that.
Rice added she was "shocked" by Trump's unsubstantiated wiretapping allegations, saying they have "no basis in fact."
ABC News' Justin Fishel, Ben Siegel and John Parkinson contributed to this report.